I have another 96' SR5 with dealer/port gray leather. I'll have to look for any Katzkin tags or markings on them. They have Toyota logos stitched into the backrest portion. I would say that the quality is poor compared to the factory leather. The stitchings are breaking and the leather on the door is delaminating.
When my Sister bought her SR5 in Utah in 2001, it was an independent private business that partnered with local Dealerships, to install Leather kits and other accessories, lift kits, etc. on new vehicles prior to or at the time of sale of the vehicle by a Dealership.
They stated that the Leather kits they used were made by Katzkin, but there were no markings denoting that visible anywhere. My opinion was that it is/was of inferior quality to the factory optional Oak Leather in my '97 SR5.